AAP cited police as saying the 27-year-old woman was driving with her mother toward Sydney on the Southern Freeway when she lost control of the vehicle and crashed through a side railing into vegetation.

Both women were unhurt, however AAP cited a statement from Wollongong police as saying: "The 27-year-old woman immediately got out of the Mitsubishi (and) ran through bush and onto the northbound lanes of the freeway.

"The woman was struck by several cars including a red Toyota Hi-Ace and a silver Holden Commodore. She sustained head injuries and died at the scene."

The drivers of both vehicles were taken to a local hospital for mandatory blood and urine testing.

"The union is saying very clearly to Coles and the other retailers that [their] practices have to change, that they are literally killing people on our roads because of the economic pressure," he said.

"What happens with Coles and other major retailers with dominating the market at 32 per cent of road transport tasks, is that they say to manufacturers, they say to farmers and they say to transport operators that you've got to do this work the cheapest and the fastest way you possibly can.

"They're price takers, which means the trucking industry either makes the decision to do the work or they don't have a job."